my understanding is a fireman needs to be a good predictor of need. Initially, the engine is fired to maximize steam production to get started and maintain sufficient steam to accelerate the train to speed. While accelerating, the fireman continues to add coal to maintain steam production.
at some point, the fireman reduces the amount of coaling anticipating a lesser need for steam in the future. Obviously nothing is instantaneous. I don't know if the fireman is thinking 1, 5, 10, more minutes in the future.
my understanding is that reducing cutoff (i.e. early cutoff) uses steam more efficiently and conserves steam. So am i correct in assuming that it's no great loss if the fireman underestimates the need for steam because the engineer can reduce cutoff (and it take a little bit longer to get to speed).
Otherwise, if the fireman doesn't reduce coaling, excess steam would be vented (wasted) as well as wasting coal and the work load on the fireman.
so i ask if my understanding is correct? but more importantly, what is the fireman/engineer looking at to know when and how much to reduce coaling?
i've heard an engineer say (youtube) that he reduces cutoff when he feels the acceleration of the train drop off. But my understanding is this is due to the reduced production of steam anticipating reaching top speed (not a limitation of the engine).
i assume there is some assessment of how hot the fire is, it's ability to produce steam and the need to maintain or change speed (in the near future) ... or is it simply knowing when based on experience?
greg - Philadelphia & Reading / Reading
Based on mthe reprint of the Reading "Firing the Steam Locomotive" (published by Periscope Film LLC in 2013), it sounds like the fireman tries to keep a consistent fire and pressure in the boiler. So it may be the boiler pressure gauge that he is watching the most. I would imagine that a steam boiler has quite a lag on it so its not an instantaneous change. Plus there are consideration on whether its a hand fired or stoker engine, the size of coal, the type of coal, is it dry or wet, how much draft is there, etc. A large part of it woud be the fireman knowing the road and whether they will be going uphill or down in the next several miles. I'm sure that there was a lot of art as much as science.
Dave H. Painted side goes up. My website : wnbranch.com
Greg, Its not that easy. A engineer could and some did enjoy working their fireman hard. A engine could be hard to fire for many reasons and the fireman would constantly be tossing coal into the firebox. If he had a good engineer and a well maintain locomotive the stroker would do the majority of the work while he would just need to watch the steam guage,water gauge, keep the fire trim and toss a shovel full of sand into the firebox from time to time..
Larry
Conductor.
Summerset Ry.
"Stay Alert, Don't get hurt Safety First!"
Definitely as much an art as a science. THe fireman absolutely had to know the line, and the habits of the engineer he worked with, to fire the most efficiently. This couldn;t be taught, this had to be learned by experience. And the stoker couldn't do it all, especially on the big Wooten firebox engines. Not to mention many well known fairly large engines were built without stokers. Some realized amazing gains once updated to include a stoker when they were no longer limited to just how much shoveling the poor guy could do in the course of several hours road time.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Cheers, the Bear.
"One difference between pessimists and optimists is that while pessimists are more often right, optimists have far more fun."
Knowing the railroad and anticipating your moves well in advance is paramount in maintaining a good fire and efficient running.
Keeping water "in the glass" can be one of those constant battles where you have to maintain your boiler feed pretty close to your steam consumption. Not too difficult of a task on fairly level railroad with easy grades, a decent steaming engine with not too many leaking staybolts, superheater tubes or flues and not too frequent stops and starts.
Hammering up a long grade with a hot fire can catch you off guard when you crest the summit, the engineer may begin braking and all your water rushes to the front of the boiler. Now you're scrambling to get the water level up which is killing your steam pressure and you're not really sure just how much water is covering that crown sheet. Surprize!
Again, the fireman becomes familiar with the territory and the "personality" of the engineer who might want you to keep a low water level, or not.
Many variables, of course. Identical engines will have very different firing characteristics, coal may have varying amounts of slack or shale in it, some railroads were better than others in buying quality coal. Water and water treatment is a big variable. You will see some engines with lots of deposits of lime on the boiler where the steam from the whistle or safety valves will evaporate and leave chalky residue.
With bad water the boiler will scale up and make heat transfer poor. The engine may be due for a boiler wash (every 30 days) and have lots of scale surrounding the bottom tubes or the tubes themselves may be plugged with ash.
Just a few things that come to mind that keep a fireman's job interesting.
I'm not sure if anyone has mentioned this excellent booklet from 1944 but it will answer many questions regarding the fireman's duties. It is a .pdf so you can download it and print it. 155 pages chocked full of fascinating information.
https://prrt1steamlocomotivetrust.org/bookclub/download.php
Written toward the end of the War and I'm sure the railroads were getting pretty stretched in finding fresh, able-bodied firemen for their locomotives.
Cheers, Ed
There is at least one British film from the '50s ("Fire little and fire often") for practice under their somewhat different conditions, and I think I have seen films for American practice, including the one from ATSF in the '20s with the wonderful animated Mikado cutaway drawing. I think some of them graphically illustrate some of the common firing situations (like letting a hole form in the firebed and let primary air through) and the effects, as well as actions to be taken.
Note the important discussion on what you do to stop popping off. The 'correct' answer (noted in the NZR manual but without full comment) is judicious but prompt use of feedwater to lower boiler temperature just the smidge needed to close the pop(s), analogous to the way you keep a little cup of cold water near even a big tub of first-boiling potatoes to hold them RIGHT at 163 degrees F on a burner that can't be accurately temperature-controlled.
There could be remarkable feats of distance done when the right fire, engine, engineer and route came together. In one of Westing's books on the PRR he describes a train going 47 miles without any need to shovel coal; presumably this included watching for thin spots or for impending clinker formation, the two sources of dark spots and damage.
One thing that may bear mentioning is a relative lack of concern for long-term boiler longevity, it being at least a tacit assumption that effective boiler life was strictly limited, some kinds of thermal damage more easily fixed than avoided (cf asbestos suits on NYC to hammer plugs into weeping flues at their chamber ends without dumping the water during quick engine turn!). In this age of preservation firing practices that stress the boiler 'needlessly' should be avoided, and it's important to recognize this even more carefully than, say, the Unit Firing or NZR references do.
rrinker Definitely as much an art as a science. THe fireman absolutely had to know the line, and the habits of the engineer he worked with, to fire the most efficiently. --Randy
Definitely as much an art as a science. THe fireman absolutely had to know the line, and the habits of the engineer he worked with, to fire the most efficiently.
Somewhere in on of my books there's a reminiscence of a retired engineer of when he first started firing. He worked on the Milwaukee Road in oil burning territory, but the need to vary firing conditions is the same. He said that his first time working with a certain old-head engineer, the old-head told him this: "When you see me putting my gloves on, it doesn't mean I'm going to pick my nose." Meaning he was going to make an adjustment to the throttle and/or cut off that was going to affect steam usage. That the fireman had better be prepared.
Jeff
Keeping the operating pressure just below pop-off activation was primary during movement. If the engine was moving 'light', little fueling would have been needed. Lifting heavy tonnage and bringing it up to speed would have meant steady, heavy firing, watching water level, fire, and stack all the time...meaning three eyeballs. Oh, watching for, and calling, signals, too...four eyeballs.
When cut-off was in the corner, meaning steam was being admitted for all but the last 15% of the piston's full travel down the cylinder, steam consumption was heavy, and that meant heavy admission of water through the checkvalves. That, in turn, meant rapid cooling of the boiler's contents if it keep up at a steady pace, say during a heavy drag up a grade with throttle wide open and cut-off near 70% or higher. If you don't want the boiler to get too cool to keep up the pace, you'd have to fire that much harder. Something has to give if it can't be kept in balance.
And, yes, the pair were expected to learn the route, and then to anticipate when the heaviest demand was to be met. Generally, lifting the train to speed, and then the intention of maintaining speed up grades, was where the boiler had to work hardest to supply horsepower. Of course, maintaining speed on some grades was impossible without help, or without accepting reduced speeds, but that brings up another discussion on the early definition of 'ruling grade'.
selectorWhen cut-off was in the corner, meaning steam was being admitted for all but the last 15% of the piston's full travel down the cylinder, steam consumption was heavy, and that meant heavy admission of water through the checkvalves. That, in turn, meant rapid cooling of the boiler's contents if it keep up at a steady pace, say during a heavy drag up a grade with throttle wide open and cut-off near 70% or higher. If you don't want the boiler to get too cool to keep up the pace, you'd have to fire that much harder.
But remember two things: feed from an injector is nearly at saturated (near-atmospheric) boiling temperature when it passes the check valve, and possibly getting toward saturation at rated boiler pressure in some of the late pumped feedwater systems, and the draft effect of the additional steam mass flow -- if the front end is correctly designed for 'automatic action' into the required performance range -- will increase draft and hence liberation of combustion gas in proportion to the increased consumption. This combination minimizes, to an extent, the prompt effect of 'balancing' continuous feedwater makeup against a good fire under the higher draft conditions. That said, it's little surprise that most engines of substantial size or power either got mechanical stokers very early or (as in the cases of PRR and D&H to name two wacky holdouts) had to run the engines considerably below the nominal steam-generation capacity of their fireboxes and convection sections...
You'd certainly balance the speed 'automatically' if pressure fell off, and I think the pressure-maintaining would self-limit around some relatively slow down-in-the-corner speed with the effect that pressure-keeping would increase if slogged down to low speed with a given cutoff.
The effect of course is more marked on an engine with limited cutoff, particularly one like the PRR I1 which is fundamentally a drag engine made intolerable with 50% limited c/o. Crank THAT reverse up into a load as common wisdom says, and you'll quickly discover the problems of torque peaking whether you maintain speed or not. Or run all the way 'down in the corner' which even with little slot ports ain't too far a way.
Two stories about firing come to mind. They are in the collection "Workin on the Railroad - Reminiscences from the days of Steam."
One is on Page 113, "It is no trouble at all for the engineer to 'knock out' the best fireman...."
The second one is on Page 127 "Pop liked to have plenty of coal."
There are other good stories in the collection from all the railroad crafts. Some appear to be actual reminiscences, while others may have been 'fictionalized' to some extent protect the innocent. It's still a good book, IMO, and I have a physical copy of it.
For those that don't:
https://books.google.com/books?id=_kV5C1ghXOQC&pg=PA142&lpg=PA142&dq=working+on+the+railroad+reminiscence+from+the+days+of+steam&source=bl&ots=rKHxwJf1-a&sig=ACfU3U3IznVl9NIOXQ-LA_Xf5Dei0TBqVQ&hl=en&ppis=_e&sa=X&ved=2ahUKEwiR5ILjz67mAhVaWs0KHYKnDVMQ6AEwBnoECAkQAQ#v=onepage&q=working%20on%20the%20railroad%20reminiscence%20from%20the%20days%20of%20steam&f=false
.
since this thread is still getting some attention, i'll pose some thoughts
dehusmanSo it may be the boiler pressure gauge that he is watching the most.
my understanding it that the boiler pressure rarely drops by much. That if it has and that's when the fireman starts adding coal it's going to drop further before it goes up again. (assume adding coal and water are coordinated; add coal before pressure drops and add water when it nears max).
i'll guess that an experienced fireman can look at a fire and know how much steam it produces and is sufficient to match the needs of the engine.
i think this is key, it's the intensity of the fire that the fireman is watchhing and controlling.
the fire needs to be pretty hot when they start and since the engine isn't moving, steam may be being vented until they get going. Assume the engineer is waiting for the fire and steam to reach a point to get started rather than waste either.
of course, the faster the locomotive moves the more steam it consumes. it's not clear if max fire/steam is needed when they start or sometime after they pick up speed.
at some point, fireman is ready to add coal to maintain the fire and the engineer reduces cutoff, reducing the consumption of steam, and either using steam more efficiently to maintain acceleration or finally giving the fireman a break, less coal, accellerating a little less as they neer top speed (on level ground)
so now the fireman is maintaining a lesser (than max) fire
at yet another point, near or after reaching top speed, the fireman maintains an even lesser fire to simply maintain speed (i.e. no acceleration).
so it seems the fire is maintained at various levels to supply sufficent steam to accelerate or maintain speed while the engineer is using cutoff to more efficiently use steam without unduly wasting steam, coal and the fireman's efforts. I'm guessing it peaks after they gain appreciable speed and drops offs before reaching top speed.
Of course, I'm assuming the engineer and fireman artfully work together, not diabolically, to anticipate the needs to reach and maintain speed over whatever grades are on the route.
gregcsince this thread is still getting some attention, i'll pose some thoughts
I'll snip and put some comments in between 'as the guns bear'...
Overmodthe fireman would be banking the fire somewhat during the deceleration to the station, and during most of the stop,
banking, i assume means to pile up the coal to prevent it from burning as quickly.
it hadn't occurred to me that the fire could be reduced, not simply wait for it to burn down.
does this mean that the fireman can adjust the fire if too hot?
gregcbanking, i assume means to pile up the coal to prevent it from burning as quickly.
I was using it in the generic sense of decreasing the intensity. It does come from practice of piling the coal from a thin layer into humps or 'banks' to restrict primary oxygen from getting through the fuel to vaporize carbon, but there are different techniques that can be used to reduce the intensity.
There are a few ways, in theory, that the fire can be decreased in intensity. One of these is to control the induced draft more carefully. UP discovered for example that back-pressure-reducing improvements could so reduce effective draft at high speed as to compromise steam generation efficiency -- I believe this is documented in Kratville's Mighty 800 book. Another method is to have better dampers, or a windbox arrangement (associated with a cellular air heater, perhaps, or with Snyder preheaters) which allows good positive control not only of the amount of primary air but also its relative distribution under the grate. You need to be somewhat careful not to get into conditions that lead to the grate elements themselves heating up and melting: this was probably a more common problem than we 'remember' with elements like FireBar grates that have a relatively high surface area and open structure, or with chain grates. Raking the fire to generate clear spots rapidly cuts down primary air to other sections, at the cost of a certain 'blast furnace' like effect at the edges of the hole, and a certain amount of trouble as the relatively cold air affects the gasdynamics of the flame plume -- relatively cold gas can then cause unexpected differential thermal expansion, leading to distortion and leaks. Higher temperatures also affect glassing of the ash and the evil of clinker formation.
Does this mean that the fireman can adjust the fire if too hot?
Yes, but the 'normal' procedure would be to 'fire ahead' using less and less fuel in your 'fire little and often' strategy and adjusting the pattern/jet action as necessary to arrive at a stable and properly-formed fire for the heat release desired.
An interesting situation to consider is that which Tuplin reported on. He encountered a crew doing way-freight switching activities with a Niagara. They had apparently laid their fire on only part of the grate ... I seem to remember it was one 'quadrant' but don't remember which one ... and were using a sliding-pressure approach to firing, at much lower than nominal (265psi) to produce only the thrust, at sensible non-slipping settings of cutoff, to do the work. One thing that struck Tuplin about this is that the consumption of both fuel and water was equivalent to that of the normal engine (a H class) that would have been doing this work, something that normal wisdom about large 4-8-4s (and even not-so-large ones in excursion service) say isn't possible.
Meanwhile there was some fascinating operation going on for those with the sense to understand what they were seeing when the Big Boy went to West Chicago during the summer. For a couple of stated operating reasons, Dickens & Barker wanted to keep the engine relatively close to nominal boiler pressure the whole time it was standing, and of course they did this with periodic adjustments to the Dickens-Barker burner (a modified Thomas burner, according to Barker).
What was interesting was that they didn't always turn on the blower. Even a little.
Apparently the natural draft through the front end was sufficient to induce enough flow to keep the burner operation stable at high turndown, and the heat release was sufficient to keep the gauge high. Later in the afternoon they started using the whistle a bit more, and they did have to crack the blower a smidge - resulting in pops lifting in no more than 5 minutes. It's interesting to consider what sort of fuel distribution and subsequent light firing would produce a similar effect, with the necessary good heat distribution in the firebox and chamber structure over time, with solid fuel like good washed 2" steam gas coal.
DR DENNIS GORDANHopefully to clarify, despite my total lack of experience, but based on my reading decades ago, that sand was necessary, only or mainly, on oil burners, since they had little or no abrasives in their exhaust, hence nothing to scour flues clean of oily soot.
It's much more that the products of oil combustion through typical burners produce relatively high amounts of that oily soot. The stuff condenses and builds up quickly. Remember that the firebox runs in an effective partial vacuum and can have substantial pockets of reducing atmosphere especially toward the rear tubesheet. As the gas flow diverges into the tubes, the unburnt material builds up back into the 'slipstream' and increasingly over the mouths of the tubes, screwing up the flow patterns. It can also accumulate on the return bends of the elements and start inducing stresses there. The sand is to clear that out, not so much to remove sooting from the firebox inner wrapper or the tube/flue walls.
We have not taken up the art and peculiarities of typical kinds of oil firing. The fundamental strategy is very different in that there is very little delay between firing changes and their effect on the fire as a whole...